This project addresses how children learn the meaning of words, by focusing on the acquisition of number words (e.g., 'two', 'three'). Number words pose a special challenge for word learners for two reasons. First, as words that refer to properties of sets, they are inherently abstract. Second, their distribution in the input overlaps with other lexical items, such as adjectives (e.g., 'little') and quantifiers (e.g., 'some'), as illustrated in 'two/little/some children'. Given this overlap, one might wonder how children learn to assign the correct meaning to these words. This project investigates the possibility that children could use the range of linguistic contexts in which number words, adjectives, and quantifiers can (and cannot) appear to draw inferences about their meanings (e.g., 'zav of the horses'must be about a quantity of horses, while 'very zav horses'cannot be). Because number words are universal across languages, this work addresses fundamental questions for language acquisition in general. The specific goals of this research are (a) to determine whether there is a set of linguistic contexts that uniquely identifies number words, and (b) whether children are sensitive enough to these contexts to use them in word learning. To address (a), an extensive corpus analysis will be conducted to determine the frequency of a set of carefully-selected of linguistic contexts (e.g., appearance in a partitive ('X of the Y'), appearance fter 'the'or adjectives, modification by adverbs such as 'exactly'and Very1, etc.) and the relative frequency with which number words, adjectives, and quantifiers appear in them. To address (b), a set of three word learning experiments using the intermodal preferential looking paradigm will be run. In each experiment, a novel word ('zav') will be used to describe a set of objects in which cardinality is pitted against the object-level property of color or size. The aim is to determine whether the linguistic context in which the novel word appears guides children to assign it either a number word meaning (e.g., 'two') or an adjective meaning (e.g., 'red', 'big'). The participants will be 2.5-year-olds, 3.5-4-year-olds, and undergraduates. PUBLIC HEALTH RELEVANCE: This work extends discussions of syntactic bootstrapping from noun and verb learning to words in the noun phrase. It has the potential to offer us a better understanding of how children learn about the meaning of number words, provide us with a more complete picture of the word learning process, and shed light on how language acts as a window into the conceptual system. This project is interdisciplinary at its core, and has implications for both cognitive psychologists working on number word learning and linguists interested in how number words are represented and are distinguished from these other lexical items.